(1) Field of the Invention
The present invention relates generally to drywall construction, and more particularly to an improved mud-on cornerbead and trim product with flexible wing portions.
(2) Description of Related Art Including Information Disclosed Under 37 CFR 1.97, 1.98
Current building construction utilizes sheets of drywall, commonly referred to as “wallboard,” to form the surfaces of interior walls of buildings. Drywall is typically formed of sheets of plaster sheathed in an outer wrapping of heavy construction paper.
In drywall construction, joints between adjacent sheets of drywall are usually covered by paper tape extending lengthwise along the joint. To finish exterior corners in wallboard construction, metal corner beads and bullnose beads are typically installed. Similarly, metal trim is used to protect and finish a wallboard edges at window and door jams, while expansion joints are inserted between sheets of wallboard at predetermined intervals within buildings.
The above-described corner bead and trim products include metal flanges projecting outwardly, which are perforated with circular holes or elongated slots, so that the trim product may be fastened to the drywall panels using nails or the like. Wet plaster is then smoothed into place to cover the metal flanges, and edges of the plaster are smoothed and feathered to cover and conceal the metal edges.
Another type of corner bead on the market is referred to as a “tape-on” or “mud-on” bead. Conventional tape-on bead includes a metal bead with a strip of paper covering the exterior surface of the metal, with wings projecting outwardly from the legs of the corner angle. Wet plaster or joint cement (“mud”) secures these paper wings to the drywall to secure the corner bead in position. Thus, the bead is fastened with mud, rather than nails or other fasteners.
While tape-on bead has found success and popularity in the market, it has its drawbacks. One problem with the use of paper strips is the scuffing and damage to the paper covering the curved nose of the bead once the bead has been installed on a corner. Because the curved nose portion of the bead is directly exposed, and has no plaster or other material covering the paper, the paper may be easily scuffed or torn with only minimal contact.
Another problem with prior art tape-on bead is the cost of the product. The paper strips must be adhered to the metal bead in a separate step from the formation of the underlying metal corner angle. This additional step can make the end product quite expensive, as compared to conventional bead without the tape-on feature.
Corner bead and other drywall trim products of the prior art have also been extruded from plastic. Plastic is preferable material over metal for a number of reasons. The major reason is the resistance of the material to rust and other natural environmental breakdown. An additional advantage of vinyl, and other plastic products, is the greater dent-resistance than its metal alternative.
The inventor herein developed an improved mud-on bead manufactured entirely of plastic or vinyl, which is the subject of co-pending application Ser. No. 11/375,997. While this co-pending application addresses many of the shortcomings of the prior art, it has been found that even this improved bead could be improved by the provision of more flexible wings or flanges, to more closely conform with the wall surface to which it is attached.